Perhaps you should try some spelling variations:
va thieu » va thiet, va hieu, va tieu
hieu van » hieu va, thien van, lieu va
hanh vai » hanh vi, hanh va, hanh tai
thuc van » thuc vat, thuc dan, thuc va
van cham » van chat, van tham, va cham
sach ky » sac ky, sach y, sach ty
xuc ban » duc ban, cuc ban, quoc ban
tu sach » thu sach, su sach, te sach
ma hoi » mai hoi, xa hoi, me hoi
vai va » mai va, dai va, hai va

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky nang ((ma hoi) OR (ma hoa)). hieu van cham ((thuc van) or (xuc ban)) hanh vai va thieu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((ma hoi) OR (ma hoa)). hieu van cham ((thuc van) OR (xuc ban)) hanh vai va thieu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((ma hoi) OR (ma hoa)). hieu van cham ((thuc van) or (xuc ban)) hanh vai va thieu".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((ma hoi) OR (ma hoa)). hieu van cham ((thuc van) or (xuc ban)) hanh vai va thieu*.